Word: strains
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Dates: during 1970-1979
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...norm. But when the environment is changed the same basic process of natural selection has a diversifying effect: the new circumstances select for the preferential survival and reproduction of variants with increased fitness for those circumstances. This Darwinian process explains a phenomenon that confused early workers: when pathogenic bacterial strains are isolated from infected hosts and then repeatedly transferred in artificial culture media they often rapidly lose virulence. We now know the mechanism by which this improved adaptation to the new environment occurs, at the expense of decreased adaptation to the old one (i.e., loss of virulence): the original strain...
...consider the probability that an inadvertently produced harmful organism might cause a laboratory infection, and let us assume the worst case: an E.coli strain producing a potent toxin absorbable from the gut, such a botulinus toxin. Such a strain would indeed present a real danger of laboratory infection. But there are a number of reasons to expect this danger to be less than that with the pathogens that are handled every day by medical bacteriologists...
...Strain K12 of E. coli has become adapted to artificial media during transfer for at least 30 years in the laboratory. Recent tests in England showed that after a dose in man much larger that what one would expect from a laboratory accident, it disappeared from the stools within a few days. Its problems of survival are analogous to those of a delicate hothouse plant thrown out to compete with the weeds in a field...
...consequences could be catastrophic. A worldwide average temperature drop of only 1° Celsius could shorten growing seasons in the temperate zones enough to threaten global food supplies. Increased heating requirements would further strain energy resources such as coal, natural...
...microscope, he found a cluster of bacilli different from any he had seen before. When he mixed these with blood from survivors of Legionnaires' disease, he found antibodies against them in 29 out of 33 specimens, which indicated that the people had prior exposure to the bacterial strain. Tests on blood from victims of the St. Elizabeths infection-which had been carefully preserved in Atlanta in hopes of some day solving that puzzle-showed identical antibodies...